How to check if ALL items in list are empty string or null, if true do something asp.net

Question

I have list of items, like this:

   user = "",
   name = null,
   surname = "",
   age = null,
   nickname = ""    

How to check if ALL items in the list are empty strings or null do something...

Answer 1

var str = "bla bla";
bool result = String.IsNullOrEmpty(str); //result is false

simply use String.IsNullOrEmpty() to validate

this should be with every string.

having you said

If All

That means &&

if (String.IsNullOrEmpty(user) && String.IsNullOrEmpty(name) &&
  String.IsNullOrEmpty(surname) && String.IsNullOrEmpty(age ) &&
  String.IsNullOrEmpty(nickname ) )
  {
   // do something
  }

The other option is String.IsNullOrWhiteSpace() which is explaining itself and includes \t (tabs) too.

UPDATE 1

According to your last comment, If this is an object

you can develop method like this:

bool IsAnyNullOrEmptyInObject(object input)
{
    foreach(PropertyInfo pInfo in input.GetType().GetProperties())
    {
        if(pInfo.PropertyType == typeof(string))
        {
            string value = (string)pInfo.GetValue(input);
            if(string.IsNullOrEmpty(value))
            {
                return true;
            }
        }
    }
    return false;
}

UPDATE 2

Base on your last comment on my answer and your comment on your Question: While it is a list of objects

Suppose your object is:

public class MyObject
{
    public string User { get; set; }
    public string Name { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
    public string NickName { get; set; }
}

and the validation method is

    private bool IsAnyNullOrEmptyInObject(MyObject input)
    {
        foreach (PropertyInfo pInfo in input.GetType().GetProperties())
        {
            if (pInfo.PropertyType == typeof(string))
            {
                string value = (string)pInfo.GetValue(input);
                if (string.IsNullOrEmpty(value))
                {
                    return true;
                }
            }
        }
        return false;
    }

Then you call it like this (I tried to make the code is simple so you get the full idea)

var myList = new List<MyObject>()
{
    new MyObject(){User = "yy", Name = "", LastName = "", Age = 0, NickName = ""},
    new MyObject(){User = "twhite", Name = "Tom", LastName = "White", Age = 0, NickName = "tom"}
};

int myListLength = myList.Count;
int emptyObjectCount = 0;
foreach (MyObject obj in myList)
{
    if (!IsAnyNullOrEmptyInObject(obj))  //<<-- I used ! to negate
    {
        emptyObjectCount++;
    };
}

if (myListLength == emptyObjectCount)
{
    //Do Somthing
}

Note that in my code I use ! to negate, you may not use it as you need/not need (method name explaining itself)

Answer 2

You can use All or Any operator from linq.

using System.Linq;
var areAllItemsNull = myItems.All(x => string.IsNullOrEmpty(x));

// `Any` could give you a better performance because it will exit after 
// find the first item that is not null or whitespace. All will walk through 
// every item in the collection. 
// `All` makes the code more readable than `Any` in my opinion.
var areAllItemsNull = !myItems.Any(x => !string.IsNullOrEmpty(x));

Answer 3

        Try this out

        List<string> listOfString = new List<string> {"", "bla", null, "Yha"};

        var allNullOrWhiteSpace = listOfString.Where(s => string.IsNullOrWhiteSpace(s)).ToList();
        var allValidStrings = listOfString.Where(s => !string.IsNullOrWhiteSpace(s)).ToList();

        foreach (var item in allNullOrWhiteSpace)
        {
            //Do something with invalid strings
        }

        foreach (var item in allValidStrings )
        {
            //Do something with valid strings
        }

Answer 4

Assuming you have List<List<string>> because thats what it sounds like. You could use this:

bool value = false;
for (int i = 0; i < list.Count(); i++)
{
    value = list[i].All(x => String.IsNullOrWhitespace(x));
}
if (value)
{
    //Do something
}

Given the question and the information provided I think this is what you need. This will take a List<List<string>> and iterate through every List<string> and check if All strings in that List<string> are null or empty using String.IsNullOrEmpty().

If it is not List<List<string>> but instead List<List<Object>> and Object has all string properties like user and name. Then this simple solution will work:

List<Object> newlist = new List<Object> { };
for (int i = 0; i < list.Count(); i++)
{
    newlist = list[i].Where(x => !String.IsNullOrEmpty(x.user) ||
                              !String.IsNullOrEmpty(x.name)).ToList();
}
if (newlist.Count() == 0)
    //Do something